Mailing List lml@lancaironline.net Message #62078
From: <Sky2high@aol.com>
Sender: <marv@lancaironline.net>
Subject: Re: [LML] Runaway RPM & manifold pressure not coming up Lancair 360/Hartzel ...
Date: Thu, 24 May 2012 23:01:15 -0400
To: <lml@lancaironline.net>
David,
 
Hard to diagnose without knowing what engine monitor you are using.  RPM can be checked with an external device. 
 
The MAP gauge is an absolute pressure sensor and should read the same as the Kollsman window when the altitude is set to sea level when th engine is not running. 
 
Scott Krueger
 
In a message dated 5/23/2012 7:19:10 A.M. Central Daylight Time, superdmp@sonic.net writes:
Hi all,
 
I've got a strange problem that I'm hoping someone has seen before.  My mechanic normally works on certified aircraft, so he's contacted Lancair; but I think the answer lies here with the real experts.
 
On a return from a cross country, I wasn't able to get my RPM and manifold pressure to 'square up' the way I wanted; but the trip did end without any major incidents(a little backfiring from the rookie pilot not slowing early enough) and I landed home safe.  I asked the mechanic to check out the airplane.  The mechanic noted that after starting the engine, the manifold pressure(vacuum) indicated down in the mid teens and stayed there.  He wasn't able to increase it either by increasing RPM or by adjusting the prop governor (blue knob).  We were able to cycle the prop and note a decrease in RPM, but the manifold pressure never came up (while the engine was running).  The pressure read normal altimeter setting with the engine off.  We had planned on a flight to see if the indications were different in the air, and figured it was just a read-out problem and not an airworthiness issue.  On the takeoff roll, I noted that the RPM's exceeded red-line on my gauges; with less than full power (I roll in power gently).  I aborted the take-off roll as it was apparent I had a runaway prop.
 
To make this all a bit more interesting, I purchased this airplane and flew 5 hours cross country back home, did an additional 15 hours of flight training, and never once added a drop of oil.  It has always been at exactly 7 qts.  I noticed I'm now at 6 qts, and on pre-flight prior to my trip home from my cross-country, I noted 6.25 qts of oil.  Oil pressure and temperature all were normal throughout.
 
Any thoughts?  I'm thinking the prop governor needs to be replaced. 
 
 
Thanx for all the great help,
Dave
 
P.S.
   Looking forward to meeting some of you in Arizona in September.
 
David Powell CRFA
(386) 868-5858
 
 

 

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